Proof press



Feb. 3, 1942. J. PETERS PROOF PRESS Filed 001:. 26, 1940 5 Sheets-Sheet l 1N VENTOR.

ATTORNEY! Feb. 3, 1942. J. PETERS 2,271,745

PROOF PRESS Filed Oct. 26, 1940 5 Sheets-Sheet 2 FIG. 2.

INVENTOR.

$06M V72 BY 7711mm ATTORNEY-f Feb. 3, 1942. J. PETERS 2,271,745

PROOF PRESS Filed Oct. 26. 1940 5 Sheets-Sheet 5 1N VENTOR.

Feb. 3, 1942. J. PETERS 2,271,745

PROOF PRES S INVENTOR.

ATTORNEYS Feb. 3, 1942. PETERS 2,271,745

PROOF PRESS Filed Oct. 26, 1940 5 Shee t sSheet 5 INVENTOR.

W f2? BY Wax/W ATTORNEY/- Patented Feb. 3, 1942 PROOF PRESS John Peters, Teaneck, N. J., assignor, by mesne assignments, to Vandercook & Sons, Chicago, 111., a corporation of Illinois Application October 26, 1940, SerialNo. 362,963

8 Claims. (01.

My invention relates to a new and improved proof press, which is used for making proofs of various kinds of printed matter, such as newspaper advertisements and the like.

The main object of the invention is to provide a proof press which is preferably actuated by electrical means, and which has improved safety means for automatically stopping the operation of the press without injuring the hand of the operator, if the hand of the operator contacts with an exposed moving part of the press.

Another object of the invention is to provide a safety control of this type which is extremely simple and sensitive, and which can be readily applied to electrically operated proof presses which are now in general use.

Another object of the invention is to provide control mechanism whereby, when the hand of the operator contacts with an exposed moving part of the press, the motor of the press will bereversed and the press will be simultaneously braked.

Another object of the invention is to provide each unit of the press which can catch the hand of the operator, with a safety bar which will operate if the hand of the operator touches said bar at either end thereof or at its middle part.

Numerous additional objects of the invention will be set forth in the annexed description and drawings which illustrate a preferred embodiment thereof.

Fig. 1 is a top plan view of a proof press which is made according to the invention.

Fig. 2 is a sectional view on the line 2-2 of Fig. 1.

Fig. 3 is a sectional view on the line 3-3 of Fig. 2.

Fig. 4 is a sectional view on the line 4-4 of Fig. 2.

Fig. 5 is a plan view on the line 5--5 of Fig. 2.

Fig. 6 is a sectional view on the line 66 of Fig. 1.

Fig. 7 is a sectional view on the line 1-1 of Fig. 5.

Fig. 8 is a general circuit diagram.

Since the proof press per se is a standard and well-known device, the principal parts thereof will be described only generally.

Referring to Fig. 2, an electric motor M is mounted upon a base H which is mounted adjustably upon the frame I of the machine. This base II can be shifted in a plane which is parallel to the plane of Fig. 2, by means of the usual adjusting screw 12 which is turned by the hand wheel 14. The threaded shank of the screw l2 passes through a tapped socket of the usual type. The motor M has a shaft which is provided with a pulley 15, which is connected by means of a belt IE to a selected pulley of a pulley unit l1, which is fixed to a countershaft I8. The belt I6 is preferably passed around the largest pulley of pulley unit l1.' This shaft [8 is provided with a pulley 19, which is smaller than any of the pulleys of the pulley unit 11. The pulley I9 is connected by means of a drive belt to a larger pulley 2| which is keyed or otherwise suitably connected to a shaft I0. The shaft 10 is provided with a sprocket 9, which is connected by a chain 8 to a sprocket 1 which is keyed to a shaft 16. The shaft 16 has a gear 5'which meshes with a larger gear 4 on the shaft 3. The usual ink-transfer roll 2 is keyed to the shaft 3. Ink is applied to the surface of the roll 2 by means of the usual turnableroll 22, part of which dips into ink which is contained in a suitable ink fountain. This ink fountain has a top wall 23 and a vertical wall 24. The shaft of .the roll 22 is mounted in movable bearings. Each bearing is actuated by a plunger 25 and a compressed rubber member 26, so that roll 22 is pressed against roll 2. Roll 22 turns in unison with roll 2.

The shaft 3 is provided with sprockets which mesh with respective longitudinal chains 21 and 28. Said sprockets can turn freely relative to shaft 3, so that said sprockets are driven wholly independently of shaft 3 and roll 2. The pitch line of one of the sprockets on the shaft 3 is indicated in Fig. 2 by the reference numeral 29. The chains 21 and 28 respectively mesh with sprockets which are keyed to the shaft 30. One of these sprockets 31 is shown in Fig. 2. The chains 21 and 28 thus form an endless conveyor. Ink transfer rolls 32, 33, 34 and 35 are mounted on respective shafts whose bearings B are connected to the chain conveyors 21 and 28. These turnable rolls 32-35 inclusive, and the connection of their bearings to the endless chains 21 and 28, are old and well-known. As the endless chains are actuated, these transfer rolls 32-35 contact with the film of ink on the surface of the rotating roll 2, so that the ink is transferred from the surface of the roll 2 to the respective surfaces of the rolls 32-35. The printing plate which is used for making the proof is located in the usual trough 31. The sheet of paper which is used for making the proof, is laid upon the top printing surface of said plate, after said surface has been inked. The transfer rolls 32-35 first apply the ink to the top printing surface of said plate. 7

After the ink has thus been applied to the top printing surface of the printing plate which is located in the trough 31, it is necessary for the operator manually to lay the sheet of paper on the top printing surface of the inked printing plate.

.,.I'ressureroll 38 has its shaft also located in bearings B, which are also connected to the chains 21 and 28. After the operator has laid a sheet 01' paper upon the inked plate, the pressure roll 36, which does not contact with the roll 2, exerts suitable wiping pressure upon the sheet of paper, so as to make the proof.

The shaft 30 is provided with an additional sprocket which meshes with the chain 35. This chain 38 meshes with an adjustable idler sprocket 39, which can be adjusted in the well-known manner in order to tighten the chain 38. The chain 38 also meshes with a smaller sprocket 4|. (Figs. 2 and 3) which is connected to the shaft 40. I

In order to provide convenient speed regulation, the countershaft l8 may be provided with a pulley unit H which includes a series of integral pulleys, as shown in Fig. 4. In Fig. 4, the belt l6 drives the largest of these pulleys of the pulley unit ll. Any other of the pulleys of unit 1 to said bearings.

printing plate, or between one of said rolls and an edge wall of the trough 31, orthe top of the printing plate.

Referring in particular toFigs. 1, 2 and 7, the bearings B of the anterior inking rolls 34 and 35 are provided with brackets 53' which are fixed As shown in detail in Fig. 7, one of the brackets 53 has a resilient switch arm or trolley-switch 54' connected thereto, said switch arm 54 being insulated from its bracket 53. Said switch arm 54 is spaced from its bracket 53 by a sheet of insulating material 55, and insulating fastenings 58 are provided between said switch arm 54 and its bracket 53. These insulating connections 58 may be ofthe well-known type whereby metal screws engage with bushings made of insulating material, said bushings being connected to the bracket 53. Said switch arm 54 makes sliding contact with a contact rail :1, which is one of the features of my invenion.

Referring to Fig. 2, the ends of the contact rail 51 are indicated respectively by the reference I! can be connected by means of the belt 43 to 30 one of the integral pulleys of another pulley unit 44, in order to provide additional speed regulation.

The pulley unit 44 turns freely upon the shaft 40. The opposite faces of this pulley unit 44 are provided with friction discs or facings 45 and 48, which are made of leather or of other suitable friction material. A clutch member 41 isslidably keyed to the shaft 40, so that said clutch member 41 can have one of its faces pressed against the friction strip 45, in order to drive said clutch member 41 and the shaft and the chain conveyor, by means of the pulley unit 44. The frame of, the machine has a brake friction strip or disc 48 fixed thereto, in order to brake the movement of the clutch member 41 and of the shaft 40 and of the endless conveyor, when the clutch member 41 is in the position which is shown in Fig. 3. The clutch member 41' is shifted by means of a pedal lever 49 which is connected to shaft 50, which is tumably mounted in the frame of the machine. A tension spring 52 yieldingly holds the pedal lever 48 in the normal position which is shown in Fig. 3. A forked shifter arm 5| is rigidly connected to the shaft 50, so that when the shaft 50 is turned counterclockwise from .the position shown in Fig. 3, the shifter arm 5| will move the clutch 41 to the left of the position shown in Fig. 3, thus unbraking the clutch 41 and connecting the same frictionally to the pulley unit 44. The shaft 40 is provided with a supplemental clutch member a, which is rigidly connected to the shaft 40. When the clutch member 41 is pressed against the adjacent friction disc 46, the pulley unit 44 is slid on the shaft 40 until the friction disc 45 contacts with the supplemental clutch member 45a, thus providing a reliable and even drive of the shaft 40 All the parts are thus actuated by the single motor M.

Accidents frequently occur with the use of a proof press, especially if it is operated rapidly, because the hand of the operator is frequently caught between one of the rolls 32-35 and the numerals 58 and 59. This contact rail 51 is connected to the frame of the machine by insulated supports.

Each bracket 53 is recessed and aplunger 50 is slidably mounted in each recess. Each plunger 8. has a head 8! which is rigidly connected to the plunger 50. Each plunger 80 has a threaded extension Ma which extends through the respective bracket 53. Each bracket 53 has a compression spring 62 which urges the plunger 50 outwardly, said outward movement being limited by the stop-nut 53, which is screwed upon the extension BOa. A switch-operating arm 55 is clamped between each nut 63 and another nut 64. A metal bushing 55 is rigidly connected to the outer end-portion of each rod ill, by means of a pin or other fastening member 51. A head 58 is provided with an extension 53 which is tumably connected to each bushing 56, by means of a pivot pin Ill. The outer end-portion of each bushing" is yoke shaped, so that each extension 59 can turn freely relative to the respective bushing 55 and the respective plunger 50s A safety bar II is rigidly connected to the heads 68. A similar safety bar Ha is connected at its ends to brackets 12, which are identical with the brackets 53. Each bracket 12 is connected to one of the bearings 13 of the shaft of the tumable roll 35. The connections between the safety bar Ha and the brackets 12 is identical with the construction shown in Fig. 7, so'that further description is not required. Eachresilient switch arm I3 corresponds to the resilient switch arm 54 of Fig. 7. Y

Trolley switch 13 contacts with the track 51 just before the trolley switch 54 moves out of contact with the track 51. There is therefore a short interval of time during which both trolley switches 54 and 13 contact with the track 51.

Therefore, if the hand of the operator is in danger of being caught either by the anterior inking roll 35 or by the pressure roll 35, said hand will contact with the respective safety bar H or Ha.

The brackets 53 are respectively provided with switch-housings I4 and 14a, in which switches S and So are respectively located: Said switches S and So are of conventional type, being known as Burgess-Micro switches. Said switches S and Sa are kept in their circuit-closing positions by means of the pressure of respective screws 15 and a, which are adjustably mounted in the respective members 65. When a plunger 68 is in the position shown in Fig. '1, which is also indicated by the full lineposition of the member 65 in Fig. 5, the switch in the respective housing 14 or 14a is closed. When the member 65 is in the broken-line position shown in Fig. 5, the switch in the respective housing 14 or 14a is automatically opened. The brackets "of the pressure roll 36 are provided with similar switches at each end of the second safety bar 1 Ia.

Therefore, if the hand of the operator strikes against the safety bar 1! adjacent its median portion, both of the rods 88 which are connected to said safety bar 1I will be pushed rearwardly, thus opening both of the switches S and Sa. If the hand of the operator strikes against the safety bar 1 I, adjacent one end thereof, the safety bar 1| is tilted from the full-line position illustrated in Fig. 5 to the broken-line position illustrated therein, thus opening the respective switch S or Sa.

If the hand of the operator strikes one of the bars, the circuit of motor M is reversed, in addition to braking the chain conveyor. When the hand is removed from the bar, the chain conveyor remains stationary, until the starting switch is closed.

In this embodiment, the motor M is a threephase motor, although the invention is not limited to any particular type of motor. Three-phase current is supplied from the mains 16, 11 and 18. The usual manually-controlled switch 19 can be is normally continuously energized, when line switch 19 is closed. One end of the secondary coil I84 is groundedand the other end is con-- operated to connect the mains 16-18 respectively to the wires 88, 8| and 62., The wires 88, 8| and 82 are respectively connected to the wires 83, 84

and 85. These wires 83, 84 and 85 are respectively provided with contact terminals 83a and 83d, 83b and 93c, and 83c and 83f. The terminals 83a, 63b and 830 are associated with respective companion terminals of wires 86, 81 and 88. The terminals 8311, 83c, and 83f are also associated with respective companion terminals of said wires 86, 81 and 88. The motor is provided with a circuit-closing switch 89 and with a reversingswitch 98, which are provided with the respective springs 9| and 92, which bias said switches to circuit-opening position. In Fig. 8, the switch 89 is shown in the circuit-closing position, and the switch 98 is shown in the circuit-opening position. These switches are operated to circuitclosing position by respective solenoids 93 and 94. The wires 86, 81 and 88 are connected to the respective terminals of the motor M. One terminal of the solenoid 93 is connected permanently to the wire 88, through wire I82a. One terminal of solenoid 94 is permanently connected by wire I82 to wire 82.

In order to start the press, the starting switch 95 is pushed manually to the circuit-closing position, so that it connects the wires 96 and 98. The manually operated starting switch 95 is normally held in the circuit-opening position by the spring 91. The manually-operated stop switch 99 is held normally in the circuit-closing position, by the spring I88. In said circuit-closing position the stopswitch 99 connects the wires I88 and I82. 3

The relay I83 is normally energized by po tver which is supplied through the secondary coil I84 of a step-down transformer. Said secondary coil I04 is inductively coupled to the primary coil I85. One end of the primary coil I85 is connected by wire I82a to the wire 88 and the other end of the primary coil I85 is connected to the wire 82 through wire I821; so that the primary coil I85 nected to one end of the coil of the relay I83. The other end of the coil of the relay I83 is connected to the end 58 of the metal track 51. The relay I83 is of the type which exerts a magnetic flux which is fixed in direction, when the coil of said relay is energized by alternating current. The circuit of relay I83 may include a conventional rectifier (not shown) so that direct current is supplied to said relay. The switch armature I86 is therefore normally held in the full-line position which is shown in Fig. 8 by the relay I83, against the force of the spring I81. In said position the switch armature I88 connects the wires I88 and I89. The spring I81 moves the switch armature I86 to the broken-line position shown in Fig. 8, when relay I83 is tie-energized.

The brake solenoid H4 is connected to the power line in parallel with the solenoid 94, so that the solenoid H4 is energized in order to release the brake. This solenoid controls a special brake, which is one of the features of the invention. As shown in Fig. 2, the plunger II5 of the solenoid H4 is pivotally connected to a lever 6 which is pivoted at II1 to a brake shoe I I8, which is pivotally connected at II9 to the frame of the machine. A companion brake shoe I28 is also pivotally connected at II9 to the frame of the machine. A link I2I is pivotally connected at I22 to the brake shoe I28, and at I23 to the lever II 6.

The operation of the device is as follows:

When line switch 19 is open and starting switch is open and stop switch 99 is closed, the forward switch 89 and the reversing switch 98 are respectively in circuit-opening positions. Spring I81 then holds switch armature I86 in the broken-line position shown in Fig. 8, in which said switch armature I86 touches the contacts at the ends of wires I88a and I-89a.

Line switch 19 is then closed by the operator. This energizes primary coil I85, whose ends are permanently connected by the respective wires I82a and I82b to the respective line wires 88 and 82. The track 51 is then grounded either by trolley switch 54 and the normally closed switches S and Sa, or by the trolley switch 13 and the corresponding pair of switches which are associated with safety bar -1Ia, or by both of the trolley switches 54 and 13 and their associated pairs of switches. P

Relay I83 is immediately energized by secondary coil I84 to move the switch armature I86 to the full-line position shown in Fig. 8, thus immediately breaking the circuit of the reversing electromagnetic device 93, which is connected in parallel to the primary coil I85.

The pedal lever 49 is then in the position shown in Fig. 3, and the tension spring 52 holds the respective friction face of the clutch member 41 with suflicient force against the brake member 48, in order to prevent any reverse movement of the endless conveyor, if the temporarily energized solenoid 93 closes the reversing switch 9| before the'circuit of solenoid 93 is broken-by the movement of switch armature I 86 to the full-line position which is shown in Fig. 8.

However, the circuit of solenoid 93 is broken substantially instantaneously by switch armature I86, before solenoid 93 can move reversing switch 98 to the circuit-closing position.

The operator now closes switch, and then 4- rleases said switch, so that it moves back to the circuit-opening position.

As soon as switch 98 is closed, the circuit of the forward solenoid or electromagnetic device 94 is closed as follows: wire 92-wire I02- through said solenoid 94-wire Bid-wire 9|- switch 99-wire 98-wire I09switch armature HIS-wire IIi9-closed stop switch 99-wire III2- wire 80.

Forward switch 99 is thus moved immediately by solenoid 94 to the circuit-closing position, before the starting switch is opened.

The circuit of solenoid 94 then remains closed, independently of starting switch 99, as follows: wire 92-wire HIT-through solenoid 94 to wire 96a-wire 99b-contact 0, blade III, contact II2-wire IDS-switch armature IDS-wire I99 closed stop switch 99-wire Il2wire 99.

The brake solenoid III is simultaneously energized with solenoid 94, as soon as switch 89 is closed, in order to release the special brake which is a feature of the invention. The brake solenoid III has one terminal connected to wire 98, and its other terminal connected to wire I02, so that its circuit is closed as follows: wire 82--wire I02 upper end of solenoid Ill-through solenoid III to wire 99-closed starting switch 95-wire 98-wire I09--member IIl9--wire I09closed stop switch 99-wire I02-wire 90.

The special brake which is controlled by brake solenoid III is released when said solenoid Ill is energized.

The circuit of the brake solenoid Ill also remains closed when the starting switch 95 is opened.

If it is desired to stop the operation of the press in normal manner, stop switch 99 is opened, while starting switch 95 is in its normally open position. This opens the circuits of solenoids 94 and Ill, thus shutting ofl the supply of current to the motor M and automatically applying the special brake which is controlled by solenoid I II. This stops the press, even though pedal lever 49 is held down.

When the hand of the operator contacts with safety bar II, one or both switches 8, So are opened, thus breaking the circuit of relay I09, and switch armature I06 is actuated immediately by spring Ill'I to close the circuit between wires Him and I080, and to open the circuit between wires I09 and I08.

The special brake which is operated by solenoid II 4 locks the chain conveyor against the force of motor M, even though the circuit of motor M is reversed when the energized solenoid 93 closes switch 90. The deenergizing of solenoid 94 permits spring 92 to open switch 99.

When the operator takes his hand away from safety bar 1I, so that switches Sc and S can close, relay I03 is re-energized to open the circuit between wires I 08a and I09a. It is therefore necessary to close the switch 95 manually, in Order to restart the apparatus.

While the motor M is reversed when the safety device is operated, there is little or no reverse movement of the endless conveyor, because the special brake prevents this, and the electromagof the switch So, is merely a convenient means for completing the control circuit and the invention is not limited thereto. Each of the elements 32-99 inclusive may be designated as an element which is connected to the conveyor and which is movable in unison with the conveyor. The trough 91 may be designated as holding means for holding a printing plate in the path of movement of said element. The member II or the member 'IIa may be designated as a safety element which is connected to the conveyor, saidsafety element being movable in unison with the conveyor and being also movable relative to the conveyor. When said safety element is moved relative to the conveyor, this discontinues the drive of the conveyor by the motor and in the preferred embodiment of the invention, this also brakes the conveyor and also reverses the driving motor. The special brake which is provided for this purpose is normally biased to inoperative position.

I have shown a preferred embodiment of my invention, but it is clear that numerous changes and omissions can be made without departing from its spirit.

I claim:

1. A proof printing-press comprising an endless conveyor, holding means adapted to hold a printing plate in the path of movement of said conveyor, an element carried by said conveyor and movable by said conveyor over said holding means, a safety member movably connected to said conveyor, said safety element being movable in unison with said conveyor and being also movable relative to said conveyor, an electric motor adapted to actuate said conveyor, control means actuated by the movement of said safety element relative to said conveyor and adapted to stop the drive of said conveyor by said motor when said safety element is moved relative to said conveyor.

2. A proof printing-press comprising-an endless conveyor, an element connected to said endless conveyor, holding means adapted to hold a printing plate in the path of movement of said element, an electric motor adapted to actuate said conveyor, a safety bar movably connected to said conveyor, said safety bar being movable in unison with said conveyor and being also movable relative to said conveyor in a direction reverse to the path of movement of said conveyor, said safety bar being also tiltable relative to said conveyor, control means actuated by the movement of said safety bar in said reverse direction and also during said tilting to discontinue the drive of said endless conveyor by said motor.

3. A proof printing-press comprising a motor, an endless conveyor adapted to be driven by said motor, an element connected to said endless conveyorand movable in unison therewith, holding means adapted to hold a printing plate in the path of movement of said element, a safety element movably connected to said conveyor, said safety element being movable in unison with said I conveyor and being also movable relative thereto,

netic device 93 is de-energized as soon as the operator takes his hand away from the safety bar II, thus automatically re-establishing the safety circuit.

The operation of the safety bar I la is identical with that of the safety bar II.

The grounding of one end of the secondary coil Ill! and the grounding of one of the terminals a brake adapted to brake the movement of said conveyor and biased to normally inoperative position, control means actuated by the movement of said safety element relative to said conveyor and adapted to discontinue the drive of said conveyor by said motor and to apply said brake means.

4. A proof printing-press comprising a motor, an endless conveyor adapted to'be driven by said motor, an element connected to said endless conveyor and movable in unison therewith, holding means adapted to hold a printing plate in the path of movement of said element, a safety element movably connected to said conveyor, said safety element being movable in unison with said conveyor and being also movable relative thereto, a brake adapted to brake the movement of said conveyor and biased to normally inoperative position, control means actuated by the movement of said safety element relative to said conveyor and adapted to discontinue the drive of said conveyor by said motor and to apply said brake means, and also to reverse said motor,

5. A proof printing-press comprising an endless conveyor, an element carried by said conveyor, holding means adapted to hold a printing plate in the path of movement of said element, an alternating current motor adapted to actuate said conveyor, a forward switch adapted to connect said motor to the power line to drive said motor in the forward direction, a reversing switch adapted to connect said motor to the power line to drive said motor in the reverse direction, said forward switch and said reversing switch being biased to normal circuit-opening positions, a forward electromagnetic device adapted to move the forward switch to circuitclosing position, a reversing electromagnetic device adapted to move the reversing switch to circuit-closing position, a transformer, the primary coil of said transformer being connected to said power line independently of said switches, a relay, a switch armature associated with said relay, the reversing electromagnetic device being connected in parallel to the circuit of said primary coil, the circuit of said reversing electromagnetic device including a first pair of spaced contacts, said switch armature being biased normally to connect said first pair of spaced contacts and thus to close the circuit of the reversing electromagnetic device when the relay is deenergized and independently of said forward switch and of said reversing switch, a second pair of spaced contacts, said switch armature being moved away from the first pair of contacts to connect the second pair of contacts when said relay is energized, the secondary coil of said transformer having one terminal thereof grounded and having the other .end thereof connected to one terminal of the relay, a contact track, the other terminal of the relay being connected to said contact track, a pair of spaced safety switches and normally closed carried by said conveyor, a safety element movably carried by said conveyor anterior said element and located and adapted to actuate said safety switches, said safety element being movable relative to the conveyor in a direction reverse to the movement of the conveyor to open both safety switches, said safety element being also tiltable to open one safety switch or the other safety switches, said conveyor having a trolley switch which contacts with said track, said track being connected in series through said trolley switch and said safety switches to the ground, the forward electromagnetic device having one terminal thereof connected to the power line independently of the previously-mentioned switches, the other terminal of the forward electromagnetic device being adapted to be connected through the forward switch to one of the second pair of contacts, the other of the second pair of contacts being connected to one of a pair of stop contacts, a stop switch normally biased to connect said stop contacts, the other stop contact being connected to the line independently of the previously-mentioned switches, starting contacts, a starting switch biased to a normal position in which it is spaced from said starting contacts, one of said starting contacts being connected to the secondmentioned contact of the forward electromag-. netic device and being also adapted to be connected through the forward switch to the firstmentioned second contact when the forward switch is closed, the other starting contact being connected to said first-mentioned second contact independentlyof the previously-mentioned switches with the exception 'of the starting switch.

6. A device according to claim 5, including a normally operative brake adapted to brake said conveyor, a brake electromagnetic device connected in parallel to said forward electromagnetic device and adapted to operate said brake to-operative position.

'7. In a printing press, the combination of the press bed, a carriage supporting a roll and movable on said bed for cooperation of the roll with a form on the bed, driving means for said carriage, control means for said driving means, and a guard element on said carriage in advance of said roll and actuatable to cause setting of said driving means control means for reversal of the drive direction of said carriage.

8. In a printing press, the combination of the press bed, a carriage movable on said bed and supporting a roll for cooperation with a printing form on said bed, driving means for said carriage, control means for said drive means located adjacent to said bed and normally set for forward drive of said carriage, a guard element on said carriage extending in front of said roll and means effectiveupon displacement of said guard element during forward travel of said carriage for effecting setting of said driving control means to stop the driving means.

JOHN PETERS. 

